Those CGI Spits were flying a bit close in formation, but the wingovers were reasonably realistic.
Ahhh yes, the CGI Mk1 Spitfires that are actually REAL.....
Dunkirk ? Filming the Aerial Scenes for the Epic Movie | Warbirds News
http://forums.airshows.co.uk/viewtopic.php?f=10&t=74081